(1) Field of Invention
This invention relates to non-aqueous liquid fabric treating composition products. More particularly, this invention relates to unitary dispenser packages for low- or no-phosphate, hydroxy polycarboxylic acid salt built non-aqueous liquid laundry detergent compositions which are stable against phase separation and gelation and are easily pourable and to the use of these packaged compositions for cleaning soiled fabrics.
(2) Discussion of Prior Art
Liquid non-aqueous heavy duty laundry detergent compositions are well known in the art. For instance, compositions of that type may comprise a liquid nonionic surfactant in which are dispersed particles of a builder as shown, for instance, in U.S. Pat. Nos. 4,316,812; 3,630,929; 4,254,466; 4,615,820; and 4,661,280.
Liquid detergents are often considered to be more convenient to employ than dry powdered or particulate products and, therefore, have found substantial favor with consumers. They may have one or more of the following advantages: readily measurable; speedily dissolved in the wash water; easily applied in concentrated solutions or dispersions to soiled areas on garments to be laundered; non-dusting; occupy less storage space. Additionally, the liquid detergents may have incorporated in their formulations materials which could not withstand drying operations without deterioration, which materials are often desirably employed in the manufacture of particulate detergent products. Although they are possessed of many advantages over unitary or particulate solid products, liquid detergents often have certain inherent disadvantages, too, which have to be overcome to produce acceptable commercial detergent products. Thus, some such products separate out on storage and others separate out on cooling and are not readily redispersed. In some cases the product viscosity changes and it becomes either too thick to pour or so thin as to appear watery. Some clear products become cloudy and others gel on standing.
To some extent these problems, particularly as they may be perceived by the consumer, may be partially or completely solved, by incorporating the detergent composition in a unitary package. By "unitary package" is meant a single use disposable package having therein an amount of fabric treating composition appropriate for a single full or partial (e.g. 1/4 or 1/2) load of laundry. For instance, for a unitary package separation of phases may not be so significant since the entire package and content is added to the washing machine.
There have been many proposals in the patent literature for unitary packages for fabric treating compositions, usually for powdery or particulate products, but also for aqueous and non-aqueous liquid formulations. Prepackaged detergent compositions provide several advantages, such as eliminating the need to measure and dispense measured quantities of bulk detergent from a large container, less dusting, less handling of potentially irritating ingredients, such as high alkalinity, bleach components, and so on.
Representative of the art relating to unitary packages for dispersing powdery, liquid or paste fabric treating or other types of compositions in aqueous media mention may be made of U.S. Pat. Nos. 3,186,869; 3,277,009; 3,322,674; 3,528,925; 3,892,905; 4,115,292; 4,348,293; 4,356,099; 4,416,791; 4,608,187; 4,610,799; 4,626,372 and Canadian Patent 1,112,534.
Clarke, et al., in U.S. Pat. No. 4,348,293, mentioned above, describe a package for powdery detergent comprising an outer water-insoluble, water-permeable bag and a water-soluble or dispersible protective inner layer. The package may be in the form of a laminate or as separate sheets, properly folded to encase the powdery detergent. The protective inner layer being essentially non-porous, avoids dusting of the powder composition during the bag filling operation and during use of the package.
For liquid detergent formulations, e.g. suspensions of detergent builder particles in liquid nonionic surfactant, although dusting may not be a problem, nevertheless the liquid phase of the composition, especially for liquid formulations of relatively low viscosity, e.g. below about 10,000 centipoise, may leak through the protective inner layer or through any imperfectly formed seams or seals. The same is true, although to a lesser extent, for more viscous liquids, pastes, gels and creams.
It has now been found that the double wall bag construction disclosed by Clarke, et al. may be adapted to any of these pourable low viscosity, high viscosity, paste, gel or cream non-aqueous liquid detergent compositions by proper selection of the material of the water-soluble or dispersible protective inner layer which will avoid leakage of the non-aqueous liquid phase but which will still dissolve or disperse in cold, warm or hot wash water within a reasonably short period of time to release their content into the wash water.
Another potential problem of the Clarke, et al. bag construction is that when the outer water-insoluble, water-permeable bag is sufficiently porous to allow rapid penetration of the wash bath water into the interior of the package to dissolve the inner water-soluble bag and release the detergent composition, if the bag is stored under high humidity conditions, or accidentally comes into contact with water, the inner water-soluble bag may be prematurely dissolved or weakened to allow leakage of the liquid contents. Therefore, in a preferred embodiment of this invention, there is provided a third outermost removable layer of water-insoluble water-impermeable material to protect the package from exposure to or contact with moisture, including atmospheric moisture.
As stated above, by providing the liquid detergent compositions in unitary packages, problem of phase separation, gelling and so on may not be perceived by the consumer and, therefore, may not appear to require special stabilizing systems or other precautions during manufacture. Nevertheless, product stability is an important consideration for the manufacturer since in many cases there may be substantial delays in time between the bulk formulation of the product and the packaging thereof into the unitary doses. Also, the bulk formulations may be made at one location and packaged at a second remote location. In either case, it is important to maintain the product as homogeneous as possible from the time the composition is first formulated until it is filled into the individual packages. It is also important that the physical characteristics of the detergent compositions, such as viscosity, gel formation, agglomeration of suspended solid particles, are not substantially changed or caused to occur over time, such as during storage, shipping or in the course of the filling operation. Any such changes in physical characteristics could seriously adversely impact on the filling operation and filling apparatus and could lead to over or underfilling of the packages, clogging of the filling nozzles or similar problems.
Therefore, in accordance with a preferred embodiment of the invention the non-aqueous heavy duty built laundry detergent composition is formulated with appropriate rheology modifiers, including one or more of viscosity modifiers, antigelling agents and physical stabilizers, in addition to the essential liquid detergent component and suspended solid particles comprising detergent builder salt, particularly hydroxy polycarboxylic acid salt, and other optional functional or aesthetic laundry detergent additives.
The washing power of synthetic nonionic surfactant detergents in laundry detergent compositions can be increased by the addition of builders. Sodium tripolyphosphate is one of the preferred builders. However, the use of polyphosphate builders in detergents does involve several disadvantages such as, for example, the tendency of the polyphosphates to hydrolyse into pyro- and orthophosphates which represent less valuable builders.
In addition, the polyphosphate content of laundry detergents has been blamed for the undesirably high phosphate content of surface water. An increased phosphate content in surface water has been found to contribute towards greater algae growth with the result that the biological equilibrium of the water can be adversely altered.
Recently enacted government legislation has been directed to reducing the amount of polyphosphates present in laundry detergents and in some jurisdictions in which polyphosphates have been a problem to require that the laundry detergents not contain any polyphosphate builders.
Therefore, still further improvements are desired in the stability and performance of built non-aqueous liquid fabric treating compositions and the means for dispensing same in a manner most convenient for consumers.